Liquid stabilizer system for polyvinyl chloride

ABSTRACT

Homogeneous liquid stabilizer compositions are provided which are useful with polyvinyl chloride resins to impart improved antistatic and antifogging properties in addition to stabilizing the resins. The stabilizer solutions are obtained using a specific procedure for blending the individual stabilizer components.

States Patent [1 Rhodes et al.

[ LIQUID STABILIZER SYSTEM FOR POLYVINYL CHLORIDE [75] Inventors: PhilipH. Rhodes; Robert L. Ahr,

both of Cincinnati, Ohio [73] Assignee: Emery Industries, Inc.,Cincinnati,

Ohio

[22] Filed: Feb. 14, 1972 [2]] Appl. No.: 226,273

[56 1' References Cited UNITED STATES PATENTS 3,558,537 l/l97l Hecker etal. 252/400 X Aug. 28, 1973 3,682,853 8/1972 Barie et al 260/23 XAPrimary Examiner-Leon D. Rosdol Assistant Examiner-Harris A. PitlickAttorney-John D. Rice, Gerald A. Baracka et a1.

[57] ABSTRACT Homogeneous liquid stabilizer compositions are providedwhich are useful with polyvinyl chloride resins to impart improvedantistatic and antifogging properties in addition to stabilizing theresins. The stabilizer solutions are obtained using a specific procedurefor blending the individual stabilizer components.

8 Claims, No Drawings LIQUID STABILIZER SYSTEM FOR POLYVINYL CHLORIDEBACKGROUND OF THE INVENTION Multi-component stabilizers are extensivelyutilized for the stabilization of polyvinyl chloride resins. Suchstabilizer systems, sometimes referred to as stabilizer packages, arecommonly therefrom. due to the inability of any one material tosufficiently protect the resins against oxidative, thermal andphotochemical degradation and to impart other desirable properties tothe Tri- (alkaryl) products. In order for a stabilizer package to beeffective, it must not only be capable of protecting the polyvinylchloride resin against loss of physical properties, discoloration orloss of optical clarity, ernbrittlement, etc., by preventing polymerdegradation, but it should also be capable of being readily anduniformly dispersed in the resin. Additionally, the stabilizer systemmust be compatible with and complement other additives employed forspecific end-use applications such as, for example, in food packaging,where antifogging and antistatic properties of the plastic compositionsare essential.

One such useful multi-component additive system has recently beendescribed in U. S. Pat. No. 3,558,537. This patent provides polyvinylchloride resin compositions characterized by-having good stability andimproved resistance to fogging. Te resins stablized in accordance withthis invention are useful for transparent plastic wraps, especially foruse with high moisture content items such as food products. Thestabilizer/antifogging system of the US. Pat. No. 3,558,537 is comprisedof partial esters derived from polyglycerol and unsaturated fatty acids,a zinc salt of a monocarboxylic fatty acid and may also contain one ormore other additives or modifiers. A particularly useful embodiment ofthe invention employs the partial ester and zinc salt in combinationwith an epoxy plasticizer and phosphite stabilizer.

While the stabilizer package described in the US. Pat. No. 3,558,537imparts extremely useful properties to the resin, it is not withoutcertain disadvantages. The four-compartment stabilizer compositionsobtained in accordance with the invention are pastes. The compositionsdo not flow readily at ambient conditions and are often lumpy,heterogeneous masses. These features present processing problems such asinability or difficulty of pumping with conventional process equipment.Another problem associated with the use of the pasty stabilizers of theUS. Pat. No. 3,558,537 is the difficutly in obtaining uniform dispersionof the mass in the polyvinyl chloride resin. The greatest drawback,however, is the tendency for phase separation (oil settles to thebottom) after preparation and upon standing. While not insurmountable,these problems do complicate the processing and equipment required ifsuch a stabilizer system is to be employed.

It would be extremely useful and advantageous if a homogeneous liquidstabilizer package capable of imparting improved stabilization andantifogging and antistatic properties to polyvinyl chlorideresinwercavailable. It would be especially useful if such a stabilizerpackage was not susceptible to phase separation upon standing. Such astabilizer composition could be easily handled and incorporated intopolyvinyl chloride compositions and homogeneous blends, uniform frombatch to batch, obtained therewith. An additional economic advantagewould'result due to the ability to employ simplified process equipmentwith such a liquid stabilizer package.

SUMMARY OF THE INVENTION specific blending technique which consists offirstv forming a solution of the metal salt, the epoxy compound and theorgano-phosphorous compound by heating at a temperature from about 125Cup to about 200C to effect solution. The polyglycerol partial ester isthen added to the resulting clear uniform solution and blendedtherewith. Stabilizer systems prepared following this procedure areliquids which do not separate upon standing and which can be readilyblended with polyvinyl chloride employing conventional processequipment. The so-prepared liquid stabilizer may also be blended withplasticizers and employed as a masterbatch. Polyvinyl chloride resinscompounded with the present liquid stabilizers exhibit a high degree ofresistivity to oxidative, thermal and photochemical degradation as wellas having improved antistatic and antifogging properties.

DETAILED DESCRIPTION In accordance with the present inventionhomogeneous lqiuid stabilizer systems are obtained by the addition ofpartial esters of polyglycerols to a solution comprised of metal saltsof carboxylic acids, organophosphorous compounds and epoxy compounds.

Any epoxy compound capable of functioning as a plasticizer may beemployed to dissolve the metal carboxylate and organophosphorouscompound but epoxidized oils are especially preferred. The epoxycompound will contain one or more epoxy groups per molecule and may beeither aliphatic, cycloaliphatic, aromatic or heterocyclic in nature.Preferably, aliphatic or cycloaliphatic epoxy compounds containing fromabout 10 to 180 carbon atoms, and more preferably from about 20 tocarbon atoms, will be employed. Epoxy higher ester compounds known to beeffective plasticizing agents-are useful for this invention. Such estersmay be derived from unsaturated alcohols and/or unsaturated acidswherein the ester is subsequently epoxidized at the site of theunsaturation. Alternatively, the unsaturated acid or alcohol may beepoxidized prior to the esterification reaction. Typical unsaturatedacids for this purpose are oleic, linoleic, linolenic,

erucic and ricinoleic acids. These may be esterified with monohydric orpolyhydric alcohols or mixtures thereof. Useful monohydric alcoholsinclude butanol, Z-ethylhexanol, octanol, isooc-tanol, lauryl alcohol,stearyl alcohol, oleyl alcohol and the like. Polyhydric alcohols mayinclude pentaerythritol, ethylene glycol, 1,2-propylene glycol,1,4-butylene glycol, neopentyl glycol, glycerol, mannitol, sorbitol,ricinoleyl alcohol,

and the like. The polyhydric alcohols may be fully or partiallyesterified.

Especially useful epoxy compounds for the instant invention are theepoxidized naturally occuring oils which consist of mixtures of higherfatty acid esters. Suitable oils include epoxidized soybean oil,epoxidized olive oil, epoxidized cottonseed oil, epoxidized coconut oil,epoxidized tall oil fatty acid esters, epoxidized tallow and the like.As an especially preferred embodi ment of the present inventionepoxidized soybean oil is employed. The useful epoxidized oils may beobtained by any known epoxidation method, such as the formic acid andsulfuric acid processes, employing any of the known epoxidizing agents.

Still other epoxy compounds may be present in combination with theaforementioned epoxy plasticizers. These epoxy compounds are usually noteffective plasticizers but may be desirable in small amounts for thestabilizing properties which they impart. Typical epoxy compounds ofthis latter type are the epoxidized monocarboxylic acids, glycidylethers of polyhydric alcohols and phenols, epoxy polyethers ofpolyhydric phenols and the like. These epoxy stabilizers .will generallynot exceed about weight percent of the total epoxy compound. a

The metal carboxylate dissolved in the epoxy plasticizer is apoly-valent metal salt of a monocarboxylic organic acid containing from6 to 36 carbon atoms. Preferably the acid will be an aliphaticmonocarboxylic acid containing from about 12 to 20 carbon atoms. Mixedacids and mixed polyvalent metals may be employed to yield useful saltsfor this invention. The mixed fatty acids are derived from fats and oilssuch as tallow, coconut oil, cottonseed oil, soybean oil, corn oil,peanut oil or the like. Typical acids which can be employed are thefollowing: caproic acid, capric acid, 2-ethylhexanoic acid, caprylicacid, pelargonic acid, hendecanoic acid, lauric acid, palmitic acid,stearic acid and the like. The polyvalent metals are preferably divalentmetals such as barium, calcium, magnesium, zinc, cadmium, tin, copper,iron, cobalt and nickel. Especially useful divalent metals are calciumand zinc or mixtures thereof since these are suitable for use innontoxic applications such as when the polyvinyl chloride resin is to beused for food-packaging film. Excellent results are obtained when zincstearate is the metal carboxylate employed with the epoxy compound andorganophosphorous compound.

Also dissolved in the epoxy plasticizer with the metal carboxylatecompound is an organophosphorous compound. The organophosphorousstabilizer compounds useful for this invention are phosphites containingat least one OR group bonded to the phosphorous atom wherein R is ahydrocarbon radical such as aryl, alkyl, alkaryl, aralkyl andcycloaliphatic or a heterocyclic group. In general, the aforementioned Rgroups will contain from about 1 to about 24 carbon atoms and morepreferably contain from about 6 to 20 carbon atoms. The phosphites ofthis invention are represented by the general formula R-O-P wherein Risone of the abovedefined groups and R. and R" are hydrogen or a radicalas defined above for R. The R groups may be the same or they may differ.Phosphite stabilizer compounds of the above type include monophenylphosphite, diphenyl phosphite, triphenyl phosphite, tricresyl phosphite,tri(octylphenyl) phosphite, tri(p-tert-nonylphenyl)phosphite,tri(nonylphenyl) phosphite, tribenzyl phosphite, tri(2- cyclohexyl)phosphite, tricyclohexyl phosphite, tricyclopentyl phosphite,tri(tetrahydrofurfuryl) phosphite, mono-isooctyl phosphite, diisooctylphosphite, triisooctyl phosphite, tridodecyl phosphite, diisooctylphenyl phosphite, diphenyl decyl phosphite, issoctyl diphenyl phosphite,tri(Z-ethylhexyl) phosphite and the like. Also useful are phosphitecompounds wherein R and R" join to form ring systems illustrated in theformulae and wherein R is a bivalent hydrocarbon radical and R is amonovalent radical, as previously defined, or a divalent radical derivedtherefrom Triphosphites, that is, where R, R and R are all hydrocarbonradicals, either the same or different, area preferred embodiment of theinstant invention. Tri(alkaryl phosphites are especially preferred withtri(nonylphenyl) phosphite being especially useful since this phosphitehas been approved by the Food and Drug Administration for use inpolyvinyl chloride resin films for food packaging applications.

To achieve the desirable stabilizer compositions of the presentinvention, that is, highly effective liquid stabilizers, it is necessarythat the metal carboxylate and phosphite compound, with any additionalstabilizer components if such are to be employed, be dissolved in theepoxy compound prior to the addition of the poly-. glycerol partialester. This is accomplished by heating a mixture containing appropriateamounts of the metal carboxylate, organophosphorous compound and epoxycompound in the temperature range from about C up to about 200C untilsolution has been effected. Preferably, while effecting solution thetemperature willnot exceed about C. All that is necessary is that thetemperature beslightly higher than the melting point of the highestmelting component in the mixture. The length of time required to bringabout solution will vary depending on the manner and temperature ofheating, efi'rcienc-y of stirring, the particular compounds employed,etc., and is not critical. As a general rule, however, the heatingshould not be continued at elevated temperatures after solution has beeneffected for such prolonged periods so as to promote decomposition ofany of the components. While no absolute time for heating can be set outwhich will encompass all the possible process variations, the point atwhich solution is effected is easily recognized since the mixture willhave been converted from an opaque, thick, white, paste-like mass to aclear and uniform, homogeneous solution. When this point is reached itmay be desirable, to insure that complete solution has been achieved, tocontinue the heating for an additional short period.

As an alternative to the above procedure, the epoxy compound and eitherone of the other components may be heated separately to obtain asolution and the third component charged later. For example, the epoxycompound and phosphite compound may be mixed and to this solution moltenmetal carboxylate added. In this manner the heat history of thethree-component mixture can be significantly reduced should this bedesirable.

The so-prepared solution may contain from about to 80 percent by weightof the organophosphorous compound but more preferably the phosphitestabilizer will comprise about 30 to 80 weight percent of the solution.The metal carboxylate will be varied from about 1 to 35 weight percentof the solution depending on the degree of stabilization required andthe particular enduse appication of the resin being stabilized.Sufficient epoxy plasticizer compound must be employed to dissolve thetwo stabilizer components. At least 5 weight percent epoxy compound isusually required, however, the amount generally will not exceed about 50percent by weight. The amount of epoxy compound required will varydepending on the solubilities of the particular stabilizer componentsand the amounts employed.

While not essential, other components may also be present with the epoxycompound, metal carboxylate and organophosphorous compound. These mayserve as supplemental stabilizers, for example where the enduse of thepolyvinyl chloride resin requires such additional stabilization. Formost film applications, the metal carboxylate, organophosphorouscompound and epoxy compound in combination with the polyglycerol partialester, which will be subsequently incorporated, is sufficient to impartthe necessary antifogging and antistatic properties and also adequatelystabilize the polyvinyl chloride resin compositions against the dele-.

terious effects of oxygen, heat and light. If desired, however, knownsupplemental stabilizer compositions may also be added. The total amountof such supplemental stabilizers will not exceed about 10 percent byweight of the solution of metal carboxylate, phosphite and epoxycompounds. Supplemental light stabilizers derived from benzophenone andits derivatives such as 2,2l-dihydroxybenzophenone and 2-hydroxybenzophenone may be added. Other stabilizers such as thosederived from 'benzotriazoles, triazines, and the phenylsalicylates mayalso be employed. Phenolic type antioxidants may also be used includingthe hindered phenols containing one or two alkyl groups, preferablytertiary alkyl groups, immediately adjacent to the hydroxyl group on thearomatic nucleus. Phenolic compounds of the above types include phenol,resorcinol, catechol, cresol, 2,6-di-t-butyl phenol,2,6-di-tbutyl-p-cresol, 2,2-bis(4-hydroxyphenyl) propane,methylene-bis(2,6-di-6-butyl phenol), methylenebis(p-cresol), and thelike. Polyvalent metal salts of substituted phenols, such as polyvalentmetal phenolates, are also effective stabilizers and may beadvantageously employed in the present invention.

Once the solution of the metal carboxylate, phosphite and epoxy compoundhas been obtained it may be allowed to stand at ambient conditions forany length of time prior to addition of the polyglycerol partial ester.Thus a masterbatch of these three components can be prepared, stored andemployed as desired by adding thereto the particular polyglycerolpartial esters.

To complete the makeup of the useful stabilizer compositions of thepresent invention apolyglycerol partial ester is added to the solutionof the metal carboxylate, phosphite and epoxy compounds. The amount ofpolyglycerol partial ester will constitute between 35 and about percentby weight of the total stabilizer package. Depending on whether thestabilization or antifogging and antistatic properties of the resin areof primary importance, the amount of polyglycerol partial ester will bevaried within the stated range. Quite unexpectedly it has been foundthat only when the components comprising the stabilizer system are addedin this manner, i.e., the polyglycerol partial ester added to an alreadyprepared solution of the other three components, are clear, homogenenousliquid stabilizer compositions obtained. Although it is essential thatthe polyglycerol partial ester be added at this stage of the reaction,the manner of addition is not critical. The partial ester may be addedto the cooled solution or it may be charged to the solution which ismaintained at a temperature up to about 160C. In the latter instance,however, when addition of the polyglycerol partial ester is made to thehot solution the resulting mixture should not be maintained at theseelevated temperatures for prolonged periods since the overalleffectiveness of the resulting stabilizer composition will be reduced.If the final stabilizer solution containing all four components issubjected to an excessive heat history the amount of'metal carboxylaterequired for acceptable stabilization is significantly increased and insome instances nearly tripled. It nevertheless may be advantageous toadd the polyglycerol partial ester to heated solutions to reduce theviscosity, facilitate handling and minimize mixing time. If thistechnique is employed, immediately after a clear solution of the fourcomponents is obtained, the temperature should be reduced. As long asthe temperature of the final solution is decreased to about C or lowerwithin about 1 hour, and more preferably within one-half hour time,after the addition of the polyglycerol partial ester no reduction in theeffectiveness of the stabilizer is observed.

The partial esters employed are obtained by the partial esterificationof polyglycerols with monocarboxylic acids. Only a portion of thehydroxyl functionality of the polyglycerol is utilized. Thepolyglycerols useful for formation of the partial esters areintermolecular glycerol ethers formed by the condensation of two or moreglycerol molecules accompanied by the elimination of water. Suchreactions are known to the art. The number of molecules condensed andmolecular weight distribution of the resulting product is primarily afunction of the temperature employed. In any event, the polyglycerolsare mixtures of products containing from 2 up to as many as 30 glycerolunits condensed. Suitable polyglycerols include, for example,diglycerol, triglycerol, tetraglycerol, pentaglycerol, hexaglycerol,heptaglycerol, octaglycerol, nonaglycerol, decaglycerol,pentadecaglycerol, triacontaglycerol and the like. The polyglycerolpartial esters useful for this invention are preferably derived frompolyglycerols containing 2 to l condensed glycerol units. The desiredphysical characteristics of the stabilizer and ultimate usage of thestabilized resin composition will dictate which polyglycerol orpolyglycerol mixture is to be employed. Other polyether polyols such asthe condensation products of sorbitol, mannitol, pentaerythritol,trimethylolpropane or mixtures thereof may also be esterified andemployed in accordance with this invention.

To obtain the partial esters of the polyglycerols one or moremonocarboxylic acids containing from about 6 to about 24 carbon atoms isesterified with the polyglycerol employing known esterificationtechniques, catalysts, etc. The esterification is conducted in such away that the polyglycerol will not be completely esterified, that is,not all the hydroxyl groups will be reacted. For the purpose of thisinvention not more than 75 percent, and preferably less than about 50percent, of the polyglycerol hydroxyl groups are reacted. Themonocarboxylic acids are preferably fatty acids which are liquids atabout room temperature, containing from about 8 to 18 carbon atoms. Theymay be saturated or contain unsaturation. Typical acids useful forpartial esterification of the polyglycerol include octanoic acid,2ethylhexanoic acid, capric acid, lauric acid, myristic acid, palmiticacid, isostearic acid, oleic acid, stearic acid, eleostearic acid,palmitoleic acid, linoleic acid, linolenic acid, ricinoleic acid and thelike. Mixtures of these and related acids may also be employed and aresometimes desirable. Such mixtures may contain both saturated andunsaturated acids and may be obtained from natural products such asvegetable and animal fats and oils. Coconut oil, cottonseed oil, linseedoil, olive oil, soybean oil, tallow, lard, tall oil, peanut oil and tungoil are typical sources useful to provide mixed acids suitable foresterification with the polyglycerol. When solely saturated acids are tobe esterified with the polyglycerol a source which provides saturatedacids may be employed or a mixtureof saturated and unsaturated acidsobtained from any source may be hydrogenated prior to use.

In accordance with the present invention the liquid four-componentstabilizer systems are useful with polyvinyl chloride homopolymers andcopolymers. They may be employed with vinyl polymers derived from one ormore vinyl monomers, i.e., containing a group, including: vinylchloride; vinyl bromide; vinyl acetate; vinylidene chloride; lower allylesters; vinly alkyl ethers; acrylic and methacrylic esters such as ethylacrylate, methyl acrylate and methyl methacrylate; acrylic acid andmethacrylic acid; acrylonitrile and methacrylonitrile; and the like.Copolymer compositions obtained by the copolymerization of vinylchloride with vinyl acetate, vinyl chloride with vinyl butyrate, vinylchloride with vinyl propionate, vinyl chloride with vinylidene chloride,vinyl chloride with meth ylacrylate, vinyl chloride with2-ethylhexylacrylate, and vinyl chloride with two or more monomers suchas mixtures of vinylidene chloride and Z-ethylhexyl acrylate are alsoeffectively stabilized. The present stabilizer compositions may be usedwith acrylonitrilebutadiene-styrene terpolymers, chloroprene polymers,butadiene-styrene polymers, butadiene-acrylonitrile copolymers,polystyrene, polyacetals and the like. These liquid stabilizers may alsobe employed with blends of one or more of the above polymercompositions. The liquid stabilizer compositions of this invention areespecially effective for use with polyvinyl chlo ride homopolymer resinssuitable for film applications.

In general, the amount of liquid stabilizer may range from about 0.5 toabout 25 parts by weight per 100 parts of the vinyl resin. Excellentresults are obtained when about 2.0 to about 6.0 parts by weight of theliquid stabilizer are employed per I00 parts by weight polyvinylchloride. Such compositions exhibit a high degree of resistance tooxidative, thermal and photochemical degradation, in addition to havingexcellent antifogging and antistatic properties.

The present stabilizer compositions, being liquids, are readilyincorporated into the vinyl polymers. Conventional mixing techniques maybe employed. The stabilizers may be used immediately after preparation,or since the present liquid compositions do not separate upon standing,they may be stored and used as required without prior mixing.

Known compounding methods for incorporating ingredients into resins suchas kneading, milling and mixing with a Banbury or ribbon mixer may beemployed. The stabilizer compositions may be added as such, added as amasterbatch solution or emulsified and the emulsion added to thepolymeric material. In general, the resins modified with the stabilizercompositions of this invention possess excellent milling characteristicsand require no special processing. The stabilizer compositions may beused in conjunction with other plasticizing agents such as dioctylphthalate, diisooctyl phthalate, dioctyl adipate, trioctyl phosphate,various polymeric plasticizers and the like. Other compoundingingredients including antioxidants, such as amines and phenols, pigmentsand other colorants, fillers, lubricants, antisticking agents, curingagents and the like may also be utilized therewith. The presentstabilizer compositions and any additional compounding ingredients maybe prepared as a masterbatch and added to the polymer as such or theliquid stabilizer and the additional ingredients may be mixed into theresin separately.

The following examples illustrate the invention more fully, however,they are not intended as a limitation on the scope thereof. In theexamples all parts and percentages are given on a weight basis unlessotherwise indicated.

EXAMPLE I A masterbatch solution of an epoxy compound, metal carboxylateand phosphite stabilizer compound was prepared by thoroughly mixing 12grams zinc stearate, grams tri(nonylphenyl) phosphite and 108 gramsepoxidized soybean oil having an oxirane value of about 6.8 to 7.0. Themixture was heated to about 150C with agitation until a clear yellowishsolution was obtained (about 1 hour). The solution was then allowed tocool and employed as a masterbatch solution for blending with thepolyglycerol partial esters.

The masterbatch solution without the addition of polyglycerol partialester, is, by itself, a useful stabilizer for polyvinyl chloride resins.For example, when parts polyvinyl chloride homopolymer (Diamond Shamrock450), 10 parts epoxidized soybean oil, 20 parts dioctyl phthalate, 0.25part stearic acid and 2.5 parts of the so-prepared masterbatch solutionwere blended and milled at 350F for approximately 5 min- EXAMPLE ll Apolyglycerol partial ester was prepared as follows:

1,980 grams (8.33 mol) of a polyglycerol having a hydroxyl value ofabout 1,280 which corresponds to about 2.3 glycerol units condensed,1,287 grams (8.33 mol) mixed fatty acids comprised of C C normal acidsand 1,155 grams (4.14 mol) oleic acid were combined in a flask. Thereaction mixture was heated (235C Max.) with stirring and allowed toreact until the acid value of the mixture was substantially nil. About30 percent of polyglycerol hydroxy groups were reacted. The reactionmixture was then cooled and stored for subsequent use. No catalyst wasemployed for this esterification reaction, however, similaresterifications were conducted employing hypophosphorous acid.

EXAMPLE III Sixty-five grams of the liquid product of Example I and 35grams of the polyglycerol partial ester of Example 11 were mixed at roomtemperature and a clear, homogeneous liquid obtained. Samples of theso-prepared solution showed no evidence of phase separation afterstorage for over 10 months at room temperature. The stabilizer solutionwas incorporated into polyvinyl chloride homopolymer in accordance withthe following recipe:

Polyvinyl chloride (Diamond Shamrock 40) 40 parts Epoxidized soybean oil(6.8-7.0 oxirane value) 9 parts Dioctyl azelate 9 parts Stearic acid 0.5part Liquid stabilizer 3.0 parts The ingredients were blended and milledat 350F for about 5 minutes. The water-white films were suitable for useas hard packaging films and had excellent lubricity or slip. The films,in addition to having excellent heat stability, also had markedlyimproved antifogging and antistatic properties.

When 35 grams of the partial ester of Example I], 4 grams zinc stearate,25 grams tri(nonylphenyl) phosphite and 36 grams epoxidized soybean oilwere combined as a unit charge and blended together at room temperaturea paste-like mass was recovered. When this mixture was heated up to ashigh as 160C a relatively clear melt was obtained but upon cooling toroom temperature and upon standing there was appreciable phaseseparation and a precipitate settled from solution. This precipitatecould not be redissolved with any amount of treatment to obtain a clearsolution. No amount of heating or any other treatment was capable ofproducing clear, homogeneous liquds which retained their homogeneityupon standing when all the four components were combined as a unitcharge.

EXAMPLE IV A liquid stabilizer composition having superior antifoggingand antistatic properties was prepared as follows: 280 grams zincstearate, 200 grams epoxidized soybean oil and 520 gramstri(nonylphenyl) phosphite were heated at 150C and the heatingterminated when a clear solution was obtained. After cooling the mixtureto about 60C, 3000 grams of the polyglycerol partial ester of Example 11was added with stirring. The resulting clear, homogeneous liquidstabilizer was compounded with polyvinyl chloride resin to prepare ameat packaging film in accordance with the following recipe:

Polyvinyl chloride homopolymer (Diamond The ingredients were blended andmilled at 350F for about 5 minutes. Thirty-five mil and 3 mil clearsheets were obtained.

Oven heat stability tests were conducted using 1 X 1 inch squares cutfrom the 35 mil sheet by placing the samples on eight glass trays fittedon a rotating device in an electric oven maintained at 375lF. Theheating is continued for minutes with one glass slide being removedafter each ten minute interval. Each slide is cooled after removal fromthe oven and the test specimen removed for observation and comparison.Samples stabilized in accordance with the present invention withstoodthe entire 80-minute heating period without failure, that is, withoutdegradation or severe discoloration and charring. After 80 minutes thesamples were clear and had an amber color.

A 3 mil sheet was employed to evaluate the antifogging properties bystretching the film over a 250 ml beaker two-thirds full of water heatedto 80C. This is is conventional test employed in the art to measureresistance of films to fogging. The film compounded in accordance withthe above recipe showed no fogging (condensation of water droplets onthe film) even after 10 minutes.

EXAMPLE V EXAMPLE VI Sixty-five grams of the liquid prepared in Example1 was combined with 35 grams of the partial ester of a polyglycerolprepared by the esterification of 1 mol diglycerol with 1.3 mols oleicacid employing hypophosphorous acid catalyst. Polyvinyl chloridehomopolymer resins containing about 3 parts of the resulting liquidstabilizer and tested in accordance wtih the abovedescribed procedureshad superior antifogging proper ties and heat stability.

EXAMPLE VII 1.5 Parts zinc stearate, 5 parts epoxidized soybean oil and10 parts tri(nonylphenyl) phosphite were heated to about 140C to effectsolution. Eighty-three parts of an ester prepared by the reaction of 1mol triglycerol with 2 mols mixed fatty acids was then added to thecooled solution. The resulting stabilizer solution was employed in thefollowing recipe:

Polyvinyl chloride copolymer mol vinyl chloride 10 mol vinyl acetate)Impact modifier (Rohm & Haas KM636) parts 10 parts ill Epoxidizedsoybean oil parts Liquid stabilizer 2.5 parts Samples of the rigid resinwere evaluated for heat stability at 360F and withstood up to 40 minutesovenaging with no serious discoloration.

EXAMPLE Vlil Diphenyl decyl phosphite (13 grams) was heated (150C max.)with 7 grams zinc stearate and 5 grams epoxidized soybean oil until aclear solution was obtained. The solution was cooled and 75 grams of theester of Example ll added thereto. The resulting stabilizer solution,while more viscous than solutions prepared with tri(nonylphenyl)phosphite, flowed readily at room temperature. Polyvinyl chloride resinhomopolymer stabilized with this stabilizer solution had good physicalproperties, heat stability and antifogging properties.

EXAMPLE IX To demonstrate the versatility of the present process for thepreparation of improved liquid stabilizers with antifogging andantistatic properties, Example IV was repeated heating to a maximumtemperature of 135C to effect solution of the zinc stearate, epoxidizedsoybean oil and tri(nonylphenyl) phosphite. The polyglycerol partialester was then added to the hot (135C) solution and the mixture cooledto about 50C within about 30 to 45 minutes. The liquid stabilizerprepared in this manner was comparable in all respects to the stabilizercomposition of Example IV.

The procedure was repeated except that the solution was not immediatelycooled after addition of the polyglycerol partial ester. The stabilizersolutions obtained were unacceptable. For example, when the mixture wasmaintained at 135C for 24 hours the brilliance of color imparted by thestabilizer is lost and water-white films are no longer obtained. Insteadthe films have a yellowish discoloration. These films, when subjected toovenaging at 375]? develop more discoloration after 10-20 minutes thanresin samples stabilized with the liquid compositions prepared inaccordance with this invention after about 80 minutes ovenaging.

We claim:

1. An improved method to obtain homogeneous liquid stabilizers in theformulation of compositions useful for improving the heat stability andantifogging and antistatic properties of vinyl polymer resins consistingessentially of (a) aliphatic or cycloaliphatic epoxy compoundscontaining from 10 to 180 carbon atoms; (b) polyvalent metal salts ofmonocarboxylic acids containing from about 6 to 36 carbon atoms; (c)organopho phorous compounds of the formula wherein R is a hydrocarbonradical containing from about 1 to 24 carbon atoms and selected from thegroup consisting of aryl, alkyl, alkaryl, aralkyl and cycloaliphatic andR and R are hydrogen or R; and (d) partial esters of polyglycerolsderived from polyglycerols containing from 2 to about 30 condensedglycerol units esterifiecl with one or more monocarboxylic acidscontaining from about 6 to 24 carbon atoms so that not more than percentof the polyglycerol hydroxyl groups are reacted comprising firstadmixing (a), (b) and (c) at a temperature from about to 200C untilsolution has been effected and thereafter blending 35 to 85 percent byweight ((1), based on the overall composition, with the resultantsolution, said first solution containing about 10 to 80 percent byweight (c), l to 35 percent by weight (b) and 5 to 50 percent by weight(a).

2. The method of claim 1 wherein in effecting the solution of (a), (b),and (c) the temperature does not exceed about 165C and (d) is added tothe hot solution and blended therein while the temperature is decreasedto about C or below within a l-hour period.

3. The method of claim 2 wherein (a) contains from about 20 to carbonatoms, (b) is the zinc salt or a mixture of calcium and zinc salts of analiphatic monocarboxylic acid containing from 12 to 20 carbon atoms, (c)is a phosphite compound with R groups containing from 6 to 20 carbonatoms, and (d) is derived from polyglycerols containing 2 to 10condensed glycerol units esterified with fatty acids containing 8 to 18carbon atoms and having less than about 50 percent of the polyglycerolhydroxyl groups reacted.

4. The process of claim 1 wherein in effecting the solution of (a), (b)and (c) the temperature does not exceed about C and prior to addition of(d) said solution is cooled to ambient conditions.

5. The method of claim 4 wherein (a) contains from about 20 to 150carbon atoms, (b) is the zinc salt or a mixture of calcium and zincsalts of an aliphatic monocarboxylic acid containing from 12 to 20carbon atoms, (0) is a phosphite compound with R groups containing from6 to 20 carbon atoms, and (d) is derived from polyglycerols containing 2to 10 condensed glycerol units esterified with fatty acids containing 8to 18 carbon atoms and having less than about 50 percent of thepolyglycerol hydroxyl groups reacted.

6. The stabilizer composition obtained by the method of claim 1 wherein(a) contains from about 20 to 150 carbon atoms, (b) is the zinc salt ora mixture of calcium and zinc salts of an aliphatic rnonocarboxylic acidcontaining from 12 to 20 carbon atoms, (c) is a pho phite compound withR groups containing from 6 to 20 carbon atoms, and (d) is derived frompolyglycerols containing 2 to 10 condensed glycerol units esterifiedwith fatty acids containing 8 to l8 carbon atoms and having less thanabout 50 percent of the polyglycerol hydroxyl groups reacted.

7. The composition of claim 6 wherein 30 to 80 weight percent (c) ispresent in the solution prior to the addition of (d).

8. The composition of claim 7 wherein (a) is an epoxidized naturallyoccurring oil, (b) is zinc stearate and (c) is tri(nonylphenyl)phosphite.

2. The method of claim 1 wherein in effecting the solution of (a), (b), and (c) the temperature does not exceed about 165*C and (d) is added to the hot solution and blended therein while the temperature is decreased to about 130*C or below within a 1-hour period.
 3. The method of claim 2 wherein (a) contains from about 20 to 150 carbon atoms, (b) is the zinc salt or a mixture of calcium and zinc salts of an aliphatic monocarboxylic acid containing from 12 to 20 carbon atoms, (c) is a phosphite compound with R groups containing from 6 to 20 carbon atoms, and (d) is derived from polyglycerols containing 2 to 10 condensed glycerol units esterified with fatty acids containing 8 to 18 carbon atoms and having less than about 50 percent of the polyglycerol hydroxyl groups reacted.
 4. The process of claim 1 wherein in effecting the solution of (a), (b) and (c) the temperature does not exceed about 165*C and prior to addition of (d) said solution is cooled to ambient conditions.
 5. The method of claim 4 wherein (a) contains from about 20 to 150 carbon atoms, (b) is the zinc salt or a mixture of calcium and zinc salts of an aliphatic monocarboxylic acid containing from 12 to 20 carbon atoms, (c) is a phosphite compound with R groups containing from 6 to 20 carbon atoms, and (d) is derived from polyglycerols containing 2 to 10 condensed glycerol units esterified with fatty acids containing 8 to 18 carbon atoms and having less than about 50 percent of the polyglycerol hydroxyl groups reacted.
 6. The stabilizer composition obtained by the method of claim 1 whereiN (a) contains from about 20 to 150 carbon atoms, (b) is the zinc salt or a mixture of calcium and zinc salts of an aliphatic monocarboxylic acid containing from 12 to 20 carbon atoms, (c) is a phosphite compound with R groups containing from 6 to 20 carbon atoms, and (d) is derived from polyglycerols containing 2 to 10 condensed glycerol units esterified with fatty acids containing 8 to 18 carbon atoms and having less than about 50 percent of the polyglycerol hydroxyl groups reacted.
 7. The composition of claim 6 wherein 30 to 80 weight percent (c) is present in the solution prior to the addition of (d).
 8. The composition of claim 7 wherein (a) is an epoxidized naturally occurring oil, (b) is zinc stearate and (c) is tri(nonylphenyl) phosphite. 